R Kotz

Medical University of Vienna, Wien, Vienna, Austria

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Publications (282)639.12 Total impact

  • The Journal of Bone and Joint Surgery 10/2015; 97(19):1585-1591. DOI:10.2106/JBJS.N.00892 · 5.28 Impact Factor
  • Rainer I Kotz ·
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    ABSTRACT: Since 1922 surgical approaches toward limb salvage in bone and soft tissue tumours have been documented. There is the famous "Umkippplastik" of Sauerbruch, the "Tikhoff-Linberg" inter-scapulo-thoracic resection or in 1943 a metallic tumour prosthesis for the hip joint in the United States (Moore, Bohlman). Since 1960 acrylic prostheses and metallic prosthesis with bone cement have been in use. Cement-free implants and the first modular ceramic prostheses were implanted in the 1970s in Vienna. At the same time successful chemotherapy in bone sarcomas was introduced by Gerald Rosen and Norman Jaffe. This was mainly the decade of custom-made prostheses. In the 1980s modular tumour prostheses with cone connection to be adopted to the needs of the patient were built intra-operatively. Since 1981 biannual international meetings (ISOLS) have pushed forward the field of bone tumour treatment to allow also tumour resection in wide borders for spine and pelvic tumours. New hope for resistant tumours could be monoclonal antibodies or even dendritic cell therapy.
    International Orthopaedics 03/2014; 38(5). DOI:10.1007/s00264-014-2315-0 · 2.11 Impact Factor
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    ABSTRACT: State of the art imaging of musculoskeletal (MSK) tumours includes conventional radiography (or CT in complex regions) and MRI of the local tumour and “whole body” modalities for staging. Whole body hybrid techniques with functional and anatomical information such as PET/CT are becoming increasingly available and can be expected to replace static staging modalities in certain indications.
    European Surgical Orthopaedics and Traumatology, 01/2014: pages 3977-3994; , ISBN: 978-3-642-34745-0
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    ABSTRACT: The failure of total hip systems caused by wear-particle-induced loosening has focused interest on factors potentially affecting wear rate. Remnants of the blasting material were reported on grit-blasted surfaces for cementless fixation. These particles are believed to cause third-body wear and implant loosening. The purpose of this study was to evaluate the early clinical and radiological outcomes of a cementless hip system with a new, contamination-free, roughened surface with regard to prosthesis-related failures. Between May 2004 and March 2009, 202 consecutive primary total hip arthroplasties (THAs) (192 patients with a mean age of 62.6 years) were performed using a cementless stem (Hipstar®) and a hemispherical acetabular cup (Trident®). At a minimum follow-up of two years, five revisions (2.5 %) due to aseptic loosening of the stem and three (1.5 %) of the cup were necessary. The cumulative rate of prostheses survival, counting revision of both components and with aseptic failure as end point, was 92.9 % at 8.8 years. Radiolucent lines up to three millimetres were evaluated in the proximal part of the femur in 61 % of cases. Although the incidence of radiolucent lines was decreased, the revision rate was considerably increased compared to other uncemented hip implants with grit-blasted surfaces in the short- to mid-term follow-up of our study. Subsequent studies are needed to confirm whether these changes in implant material and surface affect the radiological and clinical outcome in the long term.
    International Orthopaedics 10/2013; 38(4). DOI:10.1007/s00264-013-2135-7 · 2.11 Impact Factor
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    ABSTRACT: In a retrospective single-centre study 170 consecutive patients were included who received a Kotz modular prosthesis after resection of bone tumours of the proximal femur to evaluate the management of prosthetic infection. Infection occurred in 12 of 166 patients available for follow-up (six males; six females; mean age, 47 years; range, ten to 75 years) after a mean of 39 months (range, one to 166 months; infection rate, 7.2%). Mean follow-up was 54 months (range, four to 200 months). One patient died of septic shock. Two patients were treated by wound revision only. Treatment of infection in the remaining patients was one-stage revision in eight and hip disarticulation in one. Infection control by one-stage revision was achieved in five of eight patients; re-infection occurred in three patients and was successfully treated by further revision in all of them. The overall success rate for controlling infection was 83.3%.
    International Orthopaedics 10/2011; 35(10):1437-44. DOI:10.1007/s00264-010-1054-0 · 2.11 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate (a) whether pre-operative serum CRP is a predictor of survival in patients with high-grade osteosarcoma, (b) whether post-operative infection is a predictor of survival in these patients and (c) whether CRP is a predictor of post-operative infection, and especially deep prosthetic infection. In this retrospective single-centre study, pre-operative serum CRP levels in 79 patients (37 females, 42 males; average age, 18 years; mean follow-up, 46 months) undergoing resection of an osteosarcoma were correlated with clinical data and survival. The mean pre-operative serum CRP level of all 79 patients was 0.53 mg/dl (SD, 1.27 mg/dl). Patients dying of their underlying disease had significantly higher CRP levels compared to patients surviving throughout the follow-up period (1.09 mg/dl ± 2.02 mg/dl versus 0.32 mg/dl ± 0.75 mg/dl, respectively; p = 0.015). CRP levels were significantly correlated with survival (Pearson's correlation coefficient = -0.25; p = 0.026) and histological subtype (Pearson's correlation coefficient = -0.42; p < 0.001), but not with sex, age, histological response, tumour size or metastatic disease. In uni- and multivariate survival analysis, age, response to chemotherapy and serum CRP were associated with disease-specific survival. Patients with a CRP level over 1 mg/dl had a significantly lower disease-specific five-year survival of 36.7% compared to 73.8% in patients with normal CRP values (p = 0.020). Infection was not correlated with disease-specific survival. Pre-operative serum CRP levels were not correlated with post-operative infection or deep prosthetic infection. Pre-operative serum CRP seems to be an independent predictor of survival in patients with high-grade osteosarcoma. Further studies are needed to confirm these results on a large-scale basis.
    International Orthopaedics 10/2011; 35(10):1529-36. DOI:10.1007/s00264-011-1208-8 · 2.11 Impact Factor
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    ABSTRACT: In a retrospective single-centre study, 70 low-grade chondrosarcoma (LCS) (31 female/39 male patients with a mean age of 40 years) were reviewed to evaluate surgical management. The mean overall follow-up was 81 months (median: 73 months, range: 6-317 months). Seventeen lesions (24.3%) in the trunk and 53 (75.7%) in the extremities were treated by curettage (48.6%) or resection (51.5%). Local recurrence occurred in eight patients (11.4%) 18 months postoperatively (median: 18 months, range: 0-41 months). Recurrence-free survival was significantly better for patients with extremity lesions compared to truncal lesions, but was not affected by resection margin. The anatomical site "trunk" and an "intralesional" resection margin had a significant independent prognostic influence in multivariate analysis. Curettage with local adjuvants is a viable treatment option for most extremity LCS. In truncal LCS wide resection is recommended despite a potentially higher complication rate.
    International Orthopaedics 07/2011; 35(7):1049-56. DOI:10.1007/s00264-010-1065-x · 2.11 Impact Factor
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    ABSTRACT: Due to its good prognosis despite local recurrence, more and less invasive methods for surgical treatment of parosteal osteosarcoma (POS) have been described. Aim of this retrospective single-center study was to investigate differences in outcome after biological and prosthetic reconstruction. A total of 28 patients with POS, 14 females, 14 males, mean age of 27 years (median, 24 years; range 15-59 years), mean follow-up of 130 months (median, 104 months; range, 9-383 months), underwent wide tumor resection and prosthetic reconstruction (12 patients, 42.9%), less extensive resection and biological reconstruction (11 patients, 39.3%), rotationplasty (three patients, 10.7%), or amputation (two patients, 7.1%). There were two cases of local recurrence in patients with biological reconstruction and three cases of pulmonary metastases, leading to death of disease in two. Ten-year disease-specific survival was 91.1%. There was no significant difference between prosthetic and biological reconstruction in terms of local recurrence, metastasis, or functional outcome (mean MSTS Score, 85%). There were significantly more revisions in prosthetic reconstructions. Given that the resection of the tumor has clear margins, both prosthetic and biological reconstruction show similar results; prostheses allow better local tumor control, however, require more revisions over time.
    Journal of Surgical Oncology 06/2011; 103(8):782-9. DOI:10.1002/jso.21859 · 3.24 Impact Factor
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    ABSTRACT: Bone defects of the distal end of the humerus require complex reconstructions, for which standard prostheses may be insufficient. We investigated the outcomes of distal humeral reconstruction with use of a modular prosthesis. Fifty-three elbows in fifty-two patients underwent reconstruction with a modular prosthesis (twelve total humeral replacements and forty-one distal humeral replacements) after tumor resection (thirty-eight elbows) or because of massive joint degeneration (fifteen elbows). In the tumor group, twenty-three patients (twenty-four elbows) had metastatic disease and fourteen had a primary tumor. Degenerative defects of the distal end of the humerus were caused by pseudarthrosis (six elbows), prosthetic failure (five), trauma (two), osteomyelitis (one), and supracondylar fracture (one). The mean duration of follow-up for all patients was twenty-eight months (median, thirteen months; range, one to 219 months). The mean Inglis-Pellicci score in the tumor group was 84 points, and the mean Musculoskeletal Tumor Society score was 78%. Patients with total humeral reconstruction had worse scores than those with distal humeral reconstruction. Twenty-four patients died of disease at a mean of thirteen months after surgery. Local tumor control was achieved in all patients. In the revision group, the mean Inglis-Pellicci score was 76 points. The Inglis-Pellicci score was significantly better for patients in the tumor group. Eight patients (15%) had a deep periprosthetic infection, requiring amputation in one patient (2%) and prosthetic removal in two patients (4%). Four patients (8%) had the implants revised for aseptic loosening. Modular prostheses of the distal end of the humerus provide a stable reconstruction of the elbow with satisfactory function and disease control in patients with a tumor, but careful patient selection is required when the prostheses are used for revision surgery in patients without a tumor.
    The Journal of Bone and Joint Surgery 06/2011; 93(11):1064-74. DOI:10.2106/JBJS.J.00239 · 5.28 Impact Factor
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    ABSTRACT: Massive endoprostheses provide orthopaedic oncologists with many reconstructive options after tumor resection, although failure rates are high. Because the number of these procedures is limited, failure of these devices has not been studied or classified adequately. This investigation is a multicenter review of the use of segmental endoprostheses with a focus on the modes, frequency, and timing of failure. Retrospective reviews of the operative databases of five institutions identified 2174 skeletally mature patients who received a large endoprosthesis for tumor resection. Patients who had failure of the endoprosthesis were identified, and the etiology and timing of failure were noted. Similar failures were tabulated and classified on the basis of the risk of amputation and urgency of treatment. Statistical analysis was performed to identify dependent relationships among mode of failure, anatomic location, and failure timing. A literature review was performed, and similar analyses were done for these data. Five hundred and thirty-four failures were identified. Five modes of failure were identified and classified: soft-tissue failures (Type 1), aseptic loosening (Type 2), structural failures (Type 3), infection (Type 4), and tumor progression (Type 5). The most common mode of failure in this series was infection; in the literature, it was aseptic loosening. Statistical dependence was found between anatomic location and mode of failure and between mode of failure and time to failure. Significant differences were found in the incidence of failure mode Types 1, 2, 3, and 4 when polyaxial and uniaxial joints were compared. Significant dependence was also found between failure mode and anatomic location in the literature data. There are five primary modes of endoprosthetic failure, and their relative incidences are significantly different and dependent on anatomic location. Mode of failure and time to failure also show a significant dependence. Because of these relationships, cumulative reporting of segmental failures should be avoided because anatomy-specific trends will be missed. Endoprosthetic design improvements should address failure modes specific to the anatomic location.
    The Journal of Bone and Joint Surgery 03/2011; 93(5):418-29. DOI:10.2106/JBJS.J.00834 · 5.28 Impact Factor
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    ABSTRACT: Due to their rare incidence soft tissue sarcomas (STS) are often resected without clear margins. The aim of this study was to investigate the impact of re-excision of STS on survival. Out of 752 patients with STS (406 men and 346 women, average age 51 years), 310 patients were referred after an inadequate resection, 442 patients presented for primary treatment. Six hundred eighty-two patients were compared over a mean period of 65 months (median, 36 months) according to the treatment groups regarding their survival, clinical, surgical, and pathological data. The 5-year survival rate of 621 surgically treated patients was 53.9%. There was a continuous improvement in survival during the whole treatment period in the respective decades. The overall survival rate in both groups was not significantly different regardless of low- or high-grade malignancies. Patients with a re-resection did not have a higher rate of local recurrences; patients with a primary resection had a worse prognosis regarding metastases. A re-resection within 12 weeks indicated a better prognosis. An inadequate excision of a STS does not cogently mean deterioration of overall survival but necessitates an ample and quick re-resection.
    Journal of Surgical Oncology 11/2010; 102(6):626-33. DOI:10.1002/jso.21639 · 3.24 Impact Factor
  • R Kotz ·
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    ABSTRACT: The first trend-setting development of megaprostheses was initiated by Martin Salzer who introduced a ceramic prosthesis system in Vienna in 1972 for proximal humeral resection in patients with sarcoma and Ewing's sarcoma. Up until 1982, custom-made prostheses for the distal but also for the proximal femur were used for cementless implants with stem and side plates with screws. The Howmedica Modular Resection System (HMRS) exists since 1988. At the same time as the HMRS system was developed for the lower extremity, a system was also devised for the upper extremity, the Howmedica Humerus Modular Resection System, and the Global Modular Replacement System (GMRS) has been available since 2002.
    Der Orthopäde 10/2010; 39(10):922-30. DOI:10.1007/s00132-009-1567-7 · 0.36 Impact Factor
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    ABSTRACT: Local recurrence (LR) in osteosarcoma is associated with very poor prognosis. We sought to evaluate which factors correlate with LR in patients who achieved complete surgical remission with adequate margins. We analyzed 1355 patients with previously untreated high-grade central osteosarcoma of the extremities, the shoulder and the pelvis registered in neoadjuvant Cooperative Osteosarcoma Study Group trials between 1986 and 2005. Seventy-six patients developed LR. Median follow-up was 5.56 years. No participation in a study, pelvic tumor site, limb-sparing surgery, soft tissue infiltration beyond the periosteum, poor response to neoadjuvant chemotherapy, failure to complete the planned chemotherapy protocol and biopsy at a center other than the one performing the tumor resection were significantly associated with a higher LR rate. No differences were found for varying surgical margin widths. Surgical treatment at centers with small patient volume and additional surgery in the primary tumor area, other than biopsy and tumor resection, were significantly associated with a higher rate of ablative surgery. Patient enrollment in clinical trials and performing the biopsy at experienced institutions capable of undertaking the tumor resection without compromising the oncological and functional outcome should be pursued in the future.
    Annals of Oncology 10/2010; 22(5):1228-35. DOI:10.1093/annonc/mdq589 · 7.04 Impact Factor
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    ABSTRACT: The aim of this study was to prospectively evaluate our single-centre one- and five-year results of anatomically correct cementless total hip arthroplasty in unilateral and bilateral Crowe type IV high hip dislocations in ten hips following iliofemoral monotube soft tissue distraction. Six consecutive patients (five females and one male) with unilateral and two female patients with bilateral high hip dislocation with an average age of 46 years and height of dislocation up to 110 mm were treated in our institution. Limb lengthening was achieved up to 100 mm. The mean leg-length-discrepancy was -4 mm postoperatively. Harris hip score increased significantly at one year (p < 0.001) and significantly further (p < 0.05) at five years postoperative. WOMAC, VAS pain scale as well as gait and pain-free walking distance also improved significantly at follow-up. Two pin infections and one temporary peroneal nerve palsy occurred during monotube extension. Three cup protrusions that required revision surgery were observed in two patients. This study shows that iliofemoral distraction prior to total hip replacement achieves leg length equality and improved gluteal function and therefore gait in patients with Crowe type IV hip dislocation.
    International Orthopaedics 03/2010; 35(5):639-45. DOI:10.1007/s00264-010-1001-0 · 2.11 Impact Factor
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    ABSTRACT: Osteosarcoma is the most common primary malignant bone tumour. Currently osteosarcoma classification is based on histological appearance. It was the aim of this study to use a more systematic approach to osteosarcoma classification based on gene expression analysis and to identify subtype specific differentially expressed genes. We analysed the global gene expression profiles of ten osteosarcoma samples using Affymetrix U133A arrays (five osteoblastic and five non-osteoblastic osteosarcoma patients). Differential gene expression analysis yielded 75 genes up-regulated and 97 genes down-regulated in osteoblastic versus non-osteoblastic osteosarcoma samples, respectively. These included genes involved in cell growth, chemotherapy resistance, angiogenesis, steroid- and neuropeptide hormone receptor activity, acute-phase response and serotonin receptor activity and members of the Wnt/ß-catenin pathway and many others. Furthermore, we validated the highly differential expression of six genes including angiopoietin 1, IGFBP3, ferredoxin 1, BMP, decorin, and fibulin 1 in osteoblastic osteosarcoma relative to non-osteoblastic osteosarcoma. Our results show the utility of gene expression analysis to study osteosarcoma subtypes, and we identified several genes that may play a role as potential therapeutic targets in the future.
    International Orthopaedics 03/2010; 35(3):401-11. DOI:10.1007/s00264-010-0996-6 · 2.11 Impact Factor
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    ABSTRACT: COSS, the interdisciplinary Cooperative German-Austrian-Swiss Osteosarcoma Study Group, was founded in 1977 and has since registered some 3,500 bone sarcoma patients from over 200 institutions. For the purpose of the Pediatric and Adolescent Osteosarcoma Conference in Houston, March 2008, the outcomes of 2,464 consecutive patients with high-grade central osteosarcoma, who had been diagnosed between 1980 and 2005 and had been treated on neoadjuvant COSS protocols, were reviewed. Intended treatment had included surgery and multidrug chemotherapy, with high-dose methotrexate, doxorubicin, cisplatin, and ifosfamide being used in most protocols. After a median follow-up of 7.31 years for 1,654 survivors, 5- and 10-year survival estimates were 0.748/0.695 for 2,017 patients with localized extremity tumors and 0.369/0.317 for 444 patients with axial tumors or/and primary metastases, respectively. Tumor response to preoperative chemotherapy was of independent prognostic significance. Over the years, there was a major shift from amputation towards limb-salvage. This development was least evident for patients below the age of 10. While survival expectancies improved from the first to the second half of the recruitment period, no further improvement was evident within the latter period. In the manuscript, the results described above are discussed based on the findings of the previous analyses of our group.
    Cancer treatment and research 01/2010; 152:289-308. DOI:10.1007/978-1-4419-0284-9_15
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    ABSTRACT: Fracture healing is a complex physiological process caused by the interaction of cellular elements that are activated and controlled by an array of cytokines and signalling proteins [11]. This process is both temporal and spatial in nature and usually results in the formation of new bone, which is structurally and mechanically similar to the pre-fracture state [10]. For al lot of reasons this process can fail and result in non-union of bone in 10% of all fractures and in up in 50% of open fractures of the tibia. These patients develop a non-union, which leads to long-lasting inability to work, loss of employment and high social costs. These cost are estimated in a paper of Sprague 2002 to be at approximately 80,000 in case of 18 weeks delay of fracture healing [28]. The overall costs of delayed fracture healing are estimated to be at80,000 in case of 18 weeks delay of fracture healing [28]. The overall costs of delayed fracture healing are estimated to be at 14.6 million in United States alone [6].
    European Instructional Lectures, 12/2009: pages 23-36;
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    ABSTRACT: Tissue engineering has become available for cartilage repair in clinical practice. The treatment of full-thickness chondral defects in the knee with a hyaluronan-based scaffold seeded with autologous chondrocytes provides stable improvement of clinical outcome up to 7 years. Case series; Level of evidence, 4. Fifty-three patients with deep osteochondral defects in the knee were treated with Hyalograft C. The mean age at implantation was 32 +/- 12 years, the mean defect size was 4.4 +/- 1.9 cm(2), and the mean body mass index was 24.5 +/- 3.8 kg/m(2). Implantations were performed with miniarthrotomy or arthroscopy. The primary indications for implantation with Hyalograft C included young patients with a stable joint, normal knee alignment, and isolated chondral defects with otherwise healthy adjacent cartilage. The secondary indications were patients who did not meet the primary indication criteria or were salvage procedures. Forty-two patients with primary indications and 11 patients with secondary indications were evaluated. Outcome was evaluated with the International Cartilage Repair Society and International Knee Documentation Committee scales, the Lysholm score, the modified Cincinnati score, and with Kaplan-Meier survival analysis. Statistical analysis consisted of bivariate correlation analysis and unpaired, 2-tailed t tests. A highly significant increase (P <.001) in all knee scores was found in patients treated for the primary indications. Nine of 11 secondary indication cases underwent total knee arthroplasty due to persisting pain between 2 and 5 years after implantation. Graft failure occurred in 3 of 42 patients with primary indication between 6 months and 5 years after implantation. Kaplan-Meier survival demonstrated significantly different chances for survival between primary and secondary outcome and between simple, complex, and salvage cases, respectively (P <.001). Hyalograft C autograft provides clinical improvement in healthy young patients with single cartilage defects. Less complicated surgery and lower morbidity are considered advantages of the technique. The results of treatment with Hyalograft C as a salvage procedure or in patients with osteoarthritis are poor.
    The American Journal of Sports Medicine 10/2009; 37 Suppl 1(1_suppl):81S-87S. DOI:10.1177/0363546509350704 · 4.36 Impact Factor
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    ABSTRACT: Fifty-six years after the introduction of Chiari's pelvic osteotomy, we report the long-term function scores and radiographic grade of osteoarthritis in 66 patients with 80 pelvic osteotomies with a minimum followup time of 27 years (average, 32 years; range, 27-48 years). These 66 patients were those who could be contacted and who returned for a followup visit from among 450 patients operated between 1961 and 1981. Thirty-two hips (40%) in 28 patients had undergone a total joint arthroplasty after an average 26 years (range, 13-41 years). Forty-eight hips in 41 patients (60%) were not replaced, their Harris hip score being a median of 82 points (range, 37-100 points). For the 22 patients for whom we had complete radiographs the average preoperative CE angle was 11.6 degrees, 48.6 degrees (range, 31 degrees-82.8 degrees) immediately postoperatively, and 41.6 degrees (range, 13.7 degrees-90 degrees) at last followup . Despite a functional hip score in most patients retaining their native hip, the degree of osteoarthritis progressed at last followup. We observed a similar mean age at the time of osteotomy in patients converted to total hip arthroplasty and those retaining their native hip. Age at time of surgery was inversely correlated (r = -0.78) with the interval between the osteotomy and THA. In this select patient group we found good functional outcome in patients who underwent Chiari pelvic osteotomy, with a conversion rate of 40% to total hip arthroplasty a mean of 32 years after the procedure. Level of Evidence: Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence.
    Clinical Orthopaedics and Related Research 07/2009; 467(9):2215-20. DOI:10.1007/s11999-009-0910-y · 2.77 Impact Factor

  • Physikalische Medizin Rehabilitationsmedizin Kurortmedizin 04/2008; 18(2):83-86. DOI:10.1055/s-2007-991133 · 0.33 Impact Factor

Publication Stats

7k Citations
639.12 Total Impact Points


  • 1998-2011
    • Medical University of Vienna
      • Department of Orthopaedics
      Wien, Vienna, Austria
    • University of Innsbruck
      Innsbruck, Tyrol, Austria
  • 1987-2011
    • Vienna General Hospital
      Wien, Vienna, Austria
  • 1983-2010
    • University of Vienna
      • • Department of Surgery
      • • Institute of Molecular Pathology
      Wien, Vienna, Austria
  • 2007
    • Prince Court Medical Centre
      Kuala Lumpor, Kuala Lumpur, Malaysia
  • 2003
    • University of Toronto
      Toronto, Ontario, Canada
    • St Anna's Kinderspital
      Wien, Vienna, Austria
  • 2002
    • Gesellschaft für Pädiatrische Onkologie und Hämatologie
      Muenster, North Rhine-Westphalia, Germany
  • 1999
    • University of Münster
      Muenster, North Rhine-Westphalia, Germany
    • Karl-Franzens-Universität Graz
      • Institute of Psychology
      Gratz, Styria, Austria
  • 1994
    • Kyoto University
      • Department of Orthopaedic Surgery
      Kyoto, Kyoto-fu, Japan
  • 1991
    • University of Hamburg
      • Department of Paediatric Haematology and Oncology
      Hamburg, Hamburg, Germany
  • 1989
    • University of Freiburg
      Freiburg, Baden-Württemberg, Germany